Sound-reproducing mechanism for radios



A. M. KENNEDY SOUND REPRODUCING MECHANISM FOR RADIOS Nov. 4, 1930.

2 sheds-sheet '1 Filed Aug. s, 1929 INVENTOR M BY ATTOR'NFY Nov. 4,1930. A. M. KENNEDY SOUND REPRODUCING MECHANISM FOR RADIOS Filed Aug. 3,1929 2 Sheets-Sheet 2 ATTORNEY Patented Nov. 4, 1930 UNITED STATESAUBREY M. KENNEDY, or Losnnennns, CALIFORNIA SOUND-BEPRODUCING MECHANISMFOR RADIIOS Application filed August 3, 1929. Serial No. 388,270.

The object of the present invention is to provide means for use in radiobroadcasting and receiving for reproducing sound either in the sendingor the receiving of the sound 6 waves. Specifically the inventionrelates to apparatus comprising magnetically actuated tuned diaphragmsincorporated in either radio broadcasting devices or in loud speakersfor reproduction of broadcast sounds, the

diaphragms being so related to the actuating magnets that they may beselectively actuated in accordance with the character of the soundwaves.

The invention will be described with reference to the accompanyingdrawings, in which- Figure 1 is a plan view, of an embodiment of theinvention, and

Figure 2 is a sectional elevation of the same Figure 3 is a modifiedform of the apparatus;

Figure 4: is a schematic view in elevation of an embodiment of theinvention in conjunction with a microphone for broadcasting;

Figure 5 is a view in sectional elevation of a further modification, and

Figure 6 is a plan view of the same.

In the present practice of radio broadcasting and receiving, a diaphragmis employed in both the microphone and loud speaker which is selectedfor its average efliciency in the translation of the magnetic electricimpulse into vibrations or sound waves. The same diaphragm is used for asymphony orchestra as for a violin solo, and that used for a choir isthe same as used for a single voice. It is impossible to construct onediaphragm which will be suited to all musical or other sound vibrations.If a diaphragm is so constructed as to be particularly adapted for thesending or reproduction of vibrations of high pitch, that diaphragm willnot ordinarily be adapted for the best reproduction of low pitchvibrations, and there are other conditions which restrict a diaphragm ofa given construction.

Referring to Figures 1 and 2 of the drawings, it will be seen that 1 isa casing in which are mounted seven diaphragms indicated by the lettersA to G inclusive. Above each diaphragmthe casing is formed with anoutlet I indicated at 2, and the outlet may communicate with a horn orother amplifying member. Within the casing and adapted for registry witheach one of the seven diaphragms is the magneticreproducing'assembly 3which may be of usual construction. The reproducing assembly, in thesaid embodiment, is fixed, whereas casing 1 is movable, longitudinally,so that the diaphragms may selectively be brought into register with thereproducing assembly. Each diaphragm may be tuned to a note in thestandard musical scale. Assuming the device to be constructed as a loudspeaker and a violin solo is to be reproduced,

the diaphragm tuned to that particular vibration is used, forexamplediaphragm F. The casing is moved to a point where the reproducingassembly will actuate that diaphragm. Assuming that the'device isemployed as a broadcasting assembly, the action will be the same. :F orexample, announcement'may be madeby the ,broadcasterthat a violin solois to be broadcast and the direction given to use diaphragm F, whichwill be the diaphragm used by the broadcaster, and-those listening inmay accommodate their loud speakers to diaphragm F. r

Tuning of the diaphragms may be accom-- plished by various methods, asfor'example, difference in thicknesses of the diaphragms,

ditferencesin materials used,,differences in sizes, etc. 7

;-I-n. the structure of Figure -3 the .dia-

phragms are carried by a slidable frame member 4 and the reproducingassembly'is fixed within a casing 5. The casing is pro vided withaligned apertures for the passage of the slidable frame 4 so that thedia phragms may be selectively placed in register with the reproducingassembly.

In theconstruction shown in Figure 4, the

diaphragms are carried by a rotatable frame member 6 movable about anaxis 7. -At 8 I have shown, diagrammatically, a microphone, themicrophone being so related to frame member 6 that the diaphragms may besuccessively brought into operative register with the microphone foractuation by the i magnetic elements thereof. Any suitable means may beemployed for maintaining the diaphragms' in juxtaposition to themicrophone magnetic elements, as will be understood by those skilled inthe art. In Figures 5 and 6 I have shown a casing 9, a magnetic assembly10, and means for removably supporting any one ofv a pluralityoafdiaphragms, one of the diaphragms being I shown at 11. In the frontwall of the casing 10 an aperture12 is providedthrough which the I I I Idiaphragms may selectively be passed, Ar-

ranged in annular formation within casing I a I V, 9 are a plurality oflower leaf springs '13 supported by annular member 14 ofthe cas- 15 ingand supported by the top wall 9 of the V casing are a plurality of leafsprings 13*,

arranged in annularformation. Each diaphragm maybe provided with ahandle- 'by means of which:the diaphragm maybe passed through aperture12 and between the a two'sets of springs so .as to be held firmly inposition. Springs 13 may be stronger than vsprings"13 and above springs13 may be placed a rigid metallic ring 21- in register 25 with setscrews 22, by means. of which the ring may be moved downwardly so astocarry thediaphragm toward the pole pieces 23 of'the'magnetic assembly10. By reversely rotating the I thumb-screws the strongest springs 13raise thediaphragmv An equivalent'adjustment may be provided for themember 4 illustrated in Figure 3. Havingdescribed my invention, what I Iclaim and desire tosecure by'Letters Patent I I is as follows a *zflvlniradio reproducing mechanism, in combination with a magnetic assembly ofa support, diaphragm holding 'means' in said II support and a'diaphragmprovided with a 40 carrier, the diaphragm being so related to theholding means that itvmay be moved into the support and'gripped by theholding means for coaction with the magnetic assembly, and i V Vremoved-therefrom by withdrawal in the h planeof its face; a r

7 2. Afdevice constructed in accordance with I claim 1, incombiriationwith means for actllating the diaphragm toward and from theI magnetic assembly in a direction transverse U to the plane of thediaphragm face. 7 r g In testimony'whereof, I havesign'ed my name tothis specification. 7 AUBREY M. KENNEDY. A

